Renewable Energy and Conservation Chapter 13

Renewable Energy Resources Biomass Hydroelectric power Geothermal Solar—passive and active Wind generation Hydrogen power

Array of solar panels in rural Kenya Array of solar panels in rural Kenya. Silicon photovoltaic panels can be made of crystalline or amorphous silicon. Crystalline one is more efficient-that is it can convert a larger fraction of solar energy to electricity. Amorphous silicon is less efficient, costs far less to produce. The panels shown here convert solar energy to electricity, which can be stored in a battery and used to run a small appliance.

Overview of Chapter 13 Direct Solar Energy Indirect Solar Energy Heating Buildings and Water Solar Thermal Electric Generation Photovoltaic Solar Cells Indirect Solar Energy Biomass Energy Wind Energy Hydropower Other Renewable Energy Sources Geothermal Energy Tidal Energy High and Low Technology Energy Solution Hydrogen and Fuel Cells Energy Efficiency

Direct Solar Energy Varies with latitude, season, time of day, and cloud cover Areas at lower latitudes-closer to the equator receive more solar radiation annually Than do latitudes closer to the North and South Poles. More sun is received during summer than during winter because the sun is directly overhead in the summer and lower on the horizon in winter. Solar radiation is more Intense when the sun is high in the sky (noon) than when it is low in the sky (dawn or Dusk) Clouds scatter incident light and Absorb some of the sun’s energy, Thereby reducing its intensity. The South Western U.S, with its Lack of cloud cover and lower Latitude, receive the greatest amount Of solar radiation annually Whereas the Northeast receives The least.

Solar Cookers O.5 million people in rural areas of Africa, Central America, India, and china are currently using solar cookers. Solar cookers transmit solar light into the cooker, and the glass cover does not transmit the infrared wavelengths (heat) that would normally escape our of the cooker. pots containing food are placed inside the box on a black metal Plate. The solar cooker can reach a Temperature of 177 ̊C and can boil, Bake, and saute foods. In average Sunlight, a person can cook a full meal In two to four hours.

Heating Buildings and Water Passive solar energy system of putting the sun’s energy to use without requiring mechanical devices to distribute the collected heat Certain design features can enhance passive solar energy’s heating potential South facing windows (in N. hemisphere) Well insulated buildings Attic vents Overhangs and solar sunspaces it costs bit more initially than do traditional designs homes.

Several passive designs are incorporated into this home.

Solar sunspace Utilizes passive solar energy to heat and cool homes Can be added to existing homes

Heating Buildings and Water Active Solar Energy System of collecting and absorbing the sun’s energy, and using pumps or fans distribute the collected heat Most common Series of collection devices on roofs or in fields Typically a black panel or plate Used to heat water

Heating Buildings and Water Solar Thermal Electric Generation Means of producing electricity in which the sun’s energy is concentrated by mirrors or lenses to either heat a fluid filled pipe or drive a Stirling engine More efficient than other solar technologies Benefits No air pollution No contribution to global warming or acid precipitation

Solar Thermal Electric Generation Refer page number 285-286 The world’s largest solar thermal System is currently operating in The Mojave Desert in Southern California.

Photovoltaic Solar Cells A wafer or thin film of solid state materials, such as silicon or gallium arsenide, that is treated with certain metals, so that they generate electricity-that is flow of electrons-when they absorb solar energy. Convert sunlight directly into energy No pollution and minimal maintenance Used on any scale Lighted road signs Entire buildings

Photovoltaic Solar Cells Can be incorporated into building materials Roofing shingles Tile Window glass

Cost of Electrical Power Plants

Indirect Solar Energy Biomass Plant materials used as fuel Ex: wood, crop wastes, saw dust wood chips algal crops sawdust, and animal wastes Contains energy from sun via photosynthesizing plants Renewable when used no faster than it can be produced Firewood –burned Animal dung –and peat (partly decayed plant matter) Can convert to biogas or liquids Ethanol and methanol

Advantages and Disadvantages of Biomass Reduces dependence on fossil fuels Often uses waste materials If trees are planted at same rate biomass is combusted, no net increase in atmospheric CO2 Low levels of sulfur and ash Disadvantages Requires land, water and energy Compete with the growing of food crops Removal of crop residues would deplete the soil of minerals Can lead to Deforestation Desertification Soil erosion Biogas is mixture of gases mostly methane and is a clean fuel. In U.S it accounts for 3% of total U.S. Energy Production. The solid remains are used as fertilizer. Liquid biomass is ethanol and methanol. Biodiesel made from pant or animal oils.

Indirect Solar Energy Wind Energy Electric or mechanical energy obtained from surface air currents caused by solar warming of air World’s fastest growing source of energy Wind results from sun warming the atmosphere Varies in direction and magnitude New wind turbines harness wind efficiently Denmark, one of the world leaders in wind power produces 21% of its electricity using wind energy.

Wind Energy No waste- clean source of energy Biggest constraints Most profitable in rural areas with constant wind (islands, coastal areas, mountain passes, grassland Few environmental problems Kills birds and bats No waste- clean source of energy Biggest constraints Cost Public resistance Germany currently leads the world as the top producer of wind energy.

Indirect Solar Energy Hydropower Sun’s energy drive hydrologic cycle Form of renewable energy reliant on flowing or falling water to generate mechanical energy or electricity Sun’s energy drive hydrologic cycle Most efficient energy source (90%)

Hydropower Generates 19% of world’s energy The potential energy of water held back by a dam is converted to kinetic energy as the water falls down and turns turbines to generate electricity. It is the most widely used forms of solar energy. New technology May be able to utilize low flow waterways Refer to table 13.2: Advantages and Disadvantages of Dams The three Gorges Dam in China on the Yangze river and its impact

Impacts of Dams Changes natural flow of rivers A dam causes water to back up, flooding large areas of land and forming a reservoir, which destroys plant and animal habitats. Native fishes are susceptible to dams because the original river ecosystems is altered. Disrupts migratory fish patterns Potential dam breaks Natural beauty of the countryside is affected, and certain forms of wilderness recreation ar made impossible. Reservoir induced seismicity. Greater water loss by evaporation resulting in increased salinity. Schistosomiasis, which damage the liver, urinary tract, and lungs may spread. (Egypt due to Aswan Dam built on the Nile River) Wild and Scenic Rivers Act prevents the hydroelectric development of certain rivers. A dam has a limited life span for 50-200 years. It traps silt which affects agricultural lands downstream.

Other Indirect Solar Energy Ocean waves Produced by winds Has potential to turn a turbine- and create electricity Ocean Temperature Gradients Use difference in temperature of surface and deep water to create electricity. Ocean Thermal Energy Conversion (OTEC) would take advantage of the temperature difference between the warm surface water and the cold deep waters to produce electricity or to cool buildings. The first commercial OTEC plant is under construction at the National Energy Laboratory of Hawaii Authority on the Island of Hawaii.

Geothermal Energy From hot, dry rock Geothermal heat pumps Use difference in temperature between surface and subsurface Great for heating buildings Expensive installation

Geothermal energy Steam separated from hot water pumped from underground turns a turbine and generates electricity. After its use steam is condensed and pumped back into the ground. By reinjecting spent water into the ground, geothermal energy remains a renewable energy source because the cooler reinjected water can be reheated and used again.

Geothermal energy The United States is the world’s largest producer of geothermal energy. California, Nevada, Utah, and Hawaii. The world’s largest geothermal power plant is The Geysers, a geothermal field in northern California. Geothermal plants are also there in Philipines, Italy, Japan, Mexico, Indonesia, and Iceland. Geothermal energy emits hydrogen sulfide Surrounding lands may subside or sink as the water from the hotspring and underground water is removed.

Heating and cooling buildings with geothermal energy. Geothermal Heat Pumps (GHPs) take advantage of the difference in temperature between Earth’s surface and subsurface. Installation of GHPs can beexpensive. Benefits. Low operating costs. Efficient heating system Lowest carbon dioxide emissions

Tidal Energy Tides, the alternate rising and falling of the surface waters of the ocean and seas that generally occur twice each day, are the result of gravitational pull of the moon and sun. The difference in water level between high and low tides is about 0.5 m. Certain coastal regions with narrow bays have extremely large differences in water between high and low tides. The Bay of Fundy in Nova Scotia has the largest tides in the world, with 16m difference between high and low tide. Water at high tide contain enormous potential energy compared to low tide. This energy can be captured and converted into electricity. Location of tidal power plants: France, Russia, china, and Canada.

Energy conservation and Energy Efficiency Energy conservation: Using less energy, as for example, by reducing energy use and waste. This would include carpooling and lowring driving speeds. Energy efficiency: Using less energy to accomplish a given task, as for example with new technology. Both achieve same goal: Saving Energy Reduce air pollution, acid precipitation. Read A starring role in Energy Efficiency

Hydrogen as a Fuel Source Advantages to Hydrogen as a fuel source Very high energy density Can be produced from any electrical source Electrolysis (see illustration on next slide) No greenhouse gases and few other pollutants Can be use in vehicles Disadvantages to Hydrogen as a fuel source Highly volatile (requires special storage) Relatively inefficient (much of electricity is wasted in production of Hydrogen)

Hydrogen as a Fuel Source- Electrolysis

Hydrogen Fuel Cell Fuel cell Device that directly converts chemical energy into electricity Requires hydrogen from a tank and oxygen from the air Similar to a battery, only the reactants are supplied from outside source

Future Applications of Fuel Cells Vehicles Not yet commonly available Hydrogen is not yet readily available as a fuel source Batteries in cells phones or laptops Iceland plans to build the world’s first fleet of fuel cell buses, obtaining its hydrogen from geothermal and hydroelectric resources.

Energy Consumption Trends and Economics A country’s total energy consumption per unit of its gross domestic product in purchasing power parity (GDP PPP) gives one measure of its energy intensity. Lower energy intensity means that the economy is more energy efficient and does not mean a lower standard of living.

Energy-Efficient Technologies The National Appliance Energy conservation Act (NAECA) sets national efficiency standards fro refrigerators, freezers, washing machines, clothes dryers, dish washers, room air conditioners, and ovens.

Energy Efficient Technologies Compact Fluorescent light bulbs Condensing furnaces Super-insulated buildings (right) Energy efficient appliances Automobiles Aircraft technology

A Superinsulated office building in Toronto, Canada It has south facing windows with insulating glass. The building is so well insulated that it uses no furnace.

Cogeneration Production of two useful forms of energy from the same fuel

Energy Savings in Commercial Buildings

What does this cartoon imply about the relevance of energy efficiency in automobile purchasing decisions? Do you think attitudes will change? Why/why not?

You can Make a Difference Very important Read page number 304 in your Text Book.